1993年, 第19卷, 第3期　
刊出日期：1993-04-30

  

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  Crystal-Field Levels, Local Lattice Geometry and Electronic Properties of Titanium-Doped Chrysoberyl

  Chuan-Yun XIAO, Wu-Gao CHEN, Jin-Long YANG, Ke-Lin WANG, Shang-Da XIA

  理论物理通讯. 1993, 19(3): 257-264.

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  The lasing action of titanium-doped chrysoberyl crystal (Ti:BeAl₂04) is related to the crystal-field levels of Ti³⁺ ions at the mirror sites, for which two kinds of energy-level diagrams were suggested under different local symmetries. To ascertain which one is reasonabk, first-principle calculations are performed on the energy levels of Ti³⁺ ions with four cluster models. The study supports the energy-level.diagram suggested by Sugimoto et al. under C, symmetry, but disfavors that proposed by Chiba et al. under D_2h symmetry. Moreover, the results indicate that the impurity will introduce some local lattice distortion within Cs symmetry and a reasonable distorted geometrical configuration of cluster (TiO₆)^9- is proposed, with which experimental data can be satisfactorily explained and for which various electronic properties are further presented.
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  Influence of the Parabolic Potential on the Interaction of Electron-Confined Phonons in a Quantum Wire

  W. S. LI, Shi-Wei GU, T. C. AU-YEUNG, Y. Y. YEUNG

  理论物理通讯. 1993, 19(3): 265-274.

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  The Lee, Low and Pines' variational method is employed to study the interaction of electronconfined phonons within a rectangular quantum wire under an additional parabolic potential. Detailed mathematical derivation is carried out to obtain some formulire for the polaron selfenergy, the electron effective mass along the wire and the ground state energy; Using the idea of Fourier decomposition of wavefunctions, numerical calculations are performed for a typical GaAs quantum wire within the mesoscopic size. Our present results show that the effect of phonon confinement always reduces the magnitude of the electron-phonon interaction and the associated physical quwtities whereas the additional parabolic potential tends to enhance, both the electron-phonon interaction and the ground state energy. Comparing with previous calculations, our results also reveal the trends of those interesting physical quantities.
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  Properties of One Oxygen Hole Motion in a Quantum Antiferromagnet

  W. J. ZHANG, J. L. SHEN

  理论物理通讯. 1993, 19(3): 275-282.

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  By making use of the equation of motion of the Green's function method and the selfconsistent nondiagonal Fock approximation technique, we present a systematic analysis of the ground state properties of one-hole doping in the cupric oxides for the two-band model. The quant urn Bogoliu bov-de Gennes formalism is developed to study the renormalized hole motion with the effects of local distortion of spin configurations. The ground state wave function, the ground state energy and the effective mass are derived. The calculations are carried out with the variational approach.
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  Scaling and Universality in the Burst Processes of Fiber Bundles

  E. J. DING, Y. N. LU

  理论物理通讯. 1993, 19(3): 283-288.

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  The burst process in a load-carrying bundle of fibers is considered. For the homogeneous model of fiber bundles, the numerical simulation shows that large bursts near complete failure exhibit universal scaling behavior. A simple inhomogeneous model of fiher failure is also proposed. The numerical results indicate that both homogeneous and inhcmogeneous models belong to the same universality class.
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  Dynamical Behavior of the Quant um Periodically Kicked Harmonic Oscillator

  Zong-Fu JIANG

  理论物理通讯. 1993, 19(3): 289-294.

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  We explore the properties of the quantum kicked harmonic osciUation governed by the Hamiltonian H=1/2p²+1/2ω₀²x²-K cos x∑_n=-∞^∞δ(t/T - n): The classical version of this model is known to exhibit certain type of stochastic behavior. We reduce the quantum equation of the model td quantum mapping equations. Numerical results of the mappings show that the behavior of the average energy as a function of time depends on the ration of the frequency of the external (2π/T) and that of the unperturbed system wo. The energy increases first very rapidly and then the energy growth saturates for irrational ω₀T/2π. The break time is independent of the strength of the external force, but is roughly proportional to 1/ω₀T.For a fixed rational ω₀T/2πt,h e energy is damped oscillation for smaller T , a nd it is seemingly recurrent with time in the sense of Hogg and Huberman. In both cases, these behaviors of energy are independent of the strength of the external force and differ from the behavior of the quantum kicked rotator.
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  Intensity Correlation, Relaxat ion Time, Intensity Fluctuation and First-Order-Like Transition of Dye Laser

  Tie-Hai JIANG, Da-Jin WU, Li CAO

  理论物理通讯. 1993, 19(3): 295-302.

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  Statistical properties of dye laser are studied by using the colored gain-noise model which has been presented recently. We calculate the intensity correlation function and relaxation time driven by colored pump noise and white spon taneous-emission noise simultaneously. Intensity fluctuation and first-order-like transition are analyzed too in this paper. It is found that the colored gain-noise model can describe well the anomalous statistical properties of dye laser.
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  The q-Deformed SU(2) Quantum Antiferromagnetic Model

  Zhong-Yi LU, Hong YAN

  理论物理通讯. 1993, 19(3): 303-310.

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  In this paper we set up a q-analogous Holstein- Primakoff transformation (HPT) and obtain the.q-deformed spin-wave solutions. We apply a mean-field treatment that is arranged to preserve some nonlinearity of the Hamiltonian, and the results turn out to be interesting,e.g., a gapful spectrum of the elementary excitation spectrum is found, which is different from the spin-wave results for the conventionid model, and the specific heat is therefore modified greatly. The properties of the Néel state and the ground state are investigated.
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  New Braid Group Representations of C₃(D₃) and C₄(D₄) and Their Correspondent Link Polynomials

  Wei SUN, Jing-Fa LU

  理论物理通讯. 1993, 19(3): 311-318.

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  The new braid group representations of C₃(D₃) and C₄(D₄) are obtained by solving the defining relations of braid groups directly. And by introducing the appropriate diagonal matrices h, the associated link polynomials are derived also.
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  Spin Determination of Superdeformed Bands in ¹⁸⁹Hg and ¹⁹⁰Hg¹

  C. S. WU, J. Y. ZENG

  理论物理通讯. 1993, 19(3): 319-324.

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  The superdeformed bands in ¹⁸⁹Hg and ¹⁹⁰Hg are investigated. The spin value of the lowest levels observed in ¹⁸⁹Hg (fed by 366.0 keV) is assigned to be 31/2 and that of ¹⁹⁰Hg (fed by 360.0 keV) is 15, rather than the previously proposed value 14.
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  The Quantum Group Theoretic Approach to Heavy-Ion Resonances

  Zhe CHANG, Hong YAN

  理论物理通讯. 1993, 19(3): 325-336.

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  We suggest the quantum group as dynamical symmetry group of heavy-ion resonance systems. The rotation-vibrational spectra of the systems are given by the quantum groun theoretic approach without going to the detail of the bonding potential of the systems. The corresponding wave functions are obtained. Using the analytic formula of this approach, we fit the experimental data of ¹²C+¹²C and ¹²C+¹⁶O resonance systems in high accuracies. The pseudepotential is found in the quantum group symmetric model and discussed in comparison with the conventional nonlinear potential model.
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  Effective Four-Fermion Interact ions and D ynamical Breaking of Electroweak Symmetry

  Bang-Rong ZHOU

  理论物理通讯. 1993, 19(3): 337-344.

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  The minimal dynamical breaking scheme of the electroweak group SU_L(2)×U_y(1) based on the Nambu-Jona-Lasinio mechanism is expounded in the bubble approximation for the case with one generation of fermions. The configurations of allowed composite Higgs and Goldstone bosons depend on the ratio between the two independent four-fermion coupling constants and can be simply read out from the four-fermion Lagrangian. The Higgs boson mass is restricted between the double mass of the lighter and the heavier ffavor of the fermions. The implication of many-generation extension of the approach for the fine-tuning problem is conceived.
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  The Strong Interaction in Chromodynamics

  Ning HU

  理论物理通讯. 1993, 19(3): 345-356.

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  L static classical solution of nonlinear gluon field belonging to the SU(3) octet representation is obtained which is inversely proportional to the couplicg constant g, and therefore cannot be obtained by usual perturbation method. The static field is used as the potential of the relativistic wave equation of quarks in hadron states. It is found that the motion of quarks and antiquarks in all kinds of hadrons including new particles Ψ, and γ can be described by simple harmonic oscillations with small corrections due to spin-dependen t interactions.
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  Anyon Solution of an Abelian Gauge Field Coupling with Torsion

  Shu-Xue DING, He-Shan SONG, Ing AN

  理论物理通讯. 1993, 19(3): 357-360.

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  Anyon solution of an Abelian gauge field coupling with torsion of spacetime is given. It is shown that the torsion contributes to the spin and mass of the anyon proportionally. The orders of them on the surface of general neutron star are estimated in NGR theory.
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  Squeezing Transformation Involved in Solving the Dynamics of C0₂ Molecule

  Hong-Yi FAN, Jia-Fan FAN

  理论物理通讯. 1993, 19(3): 361-364.

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  For the CO₂ molecule we find a frequency-jumpsqueezing related unitary operator which plays a role in diagonalizing the Hamiltonian of internal motion of C0₂. The coordinate rep resentation of the unitary operator is derived which provides us with an alternative approach to derive the wave function of CO₂'s internal motion.
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  On e⁺+H Rearrangement Collisions in a Laser Field

  Jian-Guo WANG, Ji CHEN

  理论物理通讯. 1993, 19(3): 365-368.

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  A detailed analysis for e⁺+H rearrangement collision in the presence of a homogeneous single-mode laser field is given in both Born and Glauber approximations. The projectile laser-field interaction, the dressing effect on the target hydrogen atom and the PS atom in the final channel are considered. We discover that the differential cross section is increased in a laser field. The oscillation behavior, the rule of sum and the symmetry of absorption and emission in the low-frequency approximation are also obtained in both Born and Glauber approximations.
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  η Meson Production in High Energy Proton-Proton Collision

  L. C. LIU, D. Strottman, W. H. MA

  理论物理通讯. 1993, 19(3): 369-372.

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  Based on dominant production mechanism, η meson production in high energy protonproton collision is studied. A calculation including contributions to the total cross section of the process from S11, P11 and Dl3 resonances is performed. The theoretical prediction is in general agreement with existing data and shows that the S11 resonance dominantly contributes to the total crosssection while thecontributions from the PI1 and Dl3 resonances are negligible.
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  Q²-Dependent Parametrizations of Parton Distribution in the Constituent quark

  Lu QIAN, Da-Li XUE, Wei ZHU

  理论物理通讯. 1993, 19(3): 373-376.

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  Extracted from-the recent PMRS's distributions, the Q²-dependent parton distribution functions in constituent quarks are obtained, and the consistence of QCD evolutions between the two cases-with and without considering the level of constituent quarks in a free nucleon is discussed.
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  A Further Research on Interrelation between Mass Inequalities and Chiral Symmetry Breaking

  Bang-Rong ZHOU

  理论物理通讯. 1993, 19(3): 377-380.

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  It is deduced from some rigorous mass inequalities that in a vectorial "color" gauge theory with a zero vacuum angle the dynamical breaking of a gauged flavor chiral group could be realistic only if the fermions involved in the "color" condensates are baremassless. The mass inequalities are generalized to the case when the baremassless constituent fermions have acquired dynamical constituent masses through spontaneous chiral symmetry breaking. The results are applied to a more exact derivation of the mass constraints of the composite particles containing exotic quarks in high dimension color scheme of the ilectroweak symmetry breaking.
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  Exact Solution of the New Bosonization of the Chiral Schwinger Model

  Yan-Gang MIAO

  理论物理通讯. 1993, 19(3): 381-384.

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  A newly bosonized version of the chiral Schwinger model is quantized using Dirac's method. It. is shown to be exactly solvable and the spectrum containsp free massive boson plus an antichiral boson.